Myocardial ischemia reperfusion injury, a consequence of organ preservation and implantation, adversely impacts both early and late outcomes after heart transplantation. As heart failure is highly prevalent among the veteran population, this area of investigation is of very high significance. While neutrophils are critical mediators of myocardial ischemia reperfusion injury, little is known about their trafficking and activation requirements during this form of sterile inflammation. Utilizing our newly developed technique of intravital imaging of beating mouse hearts, we have uncovered a role for innate immune molecules in donor hearts for entry of neutrophils into the graft tissue of freshly reperfused cardiac transplants. This application proposes to study mechanisms for neutrophil recruitment during myocardial ischemia reperfusion injury of heart grafts and will allow for the development of new therapeutic strategies.